The invention relates to a method for the production of a fancy yarn, particularly such a method in which an effect configuration is predetermined and data is generated therefrom representing the selected effect configuration, and spinning adjustments are generated based on this data.
A yarn is called a fancy yarn, in which thick locations are present with predetermined larger diameters and with predetermined lengths, the so-called effects. The yarn sections located in between with a smaller diameter, in other words, the effect-free sections, are called webs. The effect data determining a fancy yarn include, in particular, the effect length, the effect diameter, the effect frequency and the respective effect-free thread length or web length.
Fancy yarns are becoming increasingly important. Areas of use are, for example, denim materials, materials for casual clothing and home textiles.
Fancy yarns can also be produced on rotor spinning machines. In this case, for example, the fiber feed to the opening roller of the rotor spinning mechanism is changed, in that the rotational speed of the draw-in rollers is varied. For this purpose, mechanical gearings are activated, which drive continuous shafts along the machine. The draw-in rollers are made to rotate by means of these shafts. The large mass of the moved parts of a drive system of this type and the gearing play, however, makes it impossible, or only with difficulty, to achieve a precise and abrupt change of the yarn thickness at the beginning and end of an effect. The speed during the spinning of fancy yarn optionally has to be sharply reduced compared to the speed when spinning effect-free yarn.
German Patent Publication DE 44 04 503 A1 describes a rotor spinning machine, in which each draw-in roller with its drive shaft is directly connected to an associated stepping motor. Each stepping motor can be activated by an activation unit. Random speed changes of the fiber band intake can be generated with a random generator. A fancy yarn with predetermined effects cannot be produced with this known rotor spinning machine. However, programs for controlling ring or rotor spinning machines, especially their delivery cylinders, have been developed, with which effects can be adjusted in a targeted manner.
The spinning machine described in German Patent Publication DE 40 41 130 A1, is used for producing fancy yarn using a program control for the effect formation. Specifications such as rotational speed of the drive motors, speeds or specific machine parameters are provided and controlled. For example, for a specific flame or effect type of the fancy yarn to be produced, the rotational speed course of the electric motor is predetermined as a desired value curve. The actual rotational speed is monitored, for example, and recorded in a control device. By maintaining the predetermined rotational speed course, the configuration of the predetermined design of the fancy yarn should be ensured. Deviations from the desired configuration of the fancy yarn, such as may occur despite adhering to specific mentioned specification values, are not recognized in the spinning machine of German Patent Publication DE 40 41 130 A1. This can lead to a reduction in the quality of the fancy yarn or even to the production of reject yarn.
The configuration of the fancy yarn during rotor spinning does not only depend on the control of the draw-in roller, but is also influenced, for example, by the low pressure in the spinning device or by the yarn rotation. It can therefore easily occur that the diverse influencing variables are inadequately coordinated and the configuration of the fancy yarn produced differs from the predetermined configuration of the fancy yarn to an undesired extent. A change in the spinning adjustments on the basis of a visual qualifying checking of the yarn often leads to costly and very time-consuming coordination processes.